Improved linearity in down-converted analog photonic link by polarization manipulation

Area of Science:

• Photonics
• Microwave Engineering
• Signal Processing

Background:

• Analog photonic links are crucial for high-frequency signal transmission.
• Linearity is a key performance metric, often limited by distortion.
• Third-order inter-modulation distortion (IMD3) degrades signal quality.

Purpose of the Study:

• To propose and demonstrate a novel method for enhancing the linearity of down-converted analog photonic links.
• To suppress third-order inter-modulation distortion (IMD3) in a 10-GHz to 100-MHz down-conversion scenario.
• To improve the spurious-free dynamic range (SFDR) of the photonic link.

Main Methods:

• The proposed method utilizes two phase modulators, a polarizer, and an optical filter.
• Optimization of transverse-electric (TE) and transverse-magnetic (TM) mode angles was performed.
• Experimental down-conversion of a 10-GHz microwave signal to a 100-MHz intermediate frequency was conducted.

Main Results:

• Successful down-conversion of a 10-GHz microwave signal to a 100-MHz intermediate frequency.
• Significant suppression of third-order inter-modulation distortion (IMD3) was achieved.
• IMD3 was suppressed by over 14 dB, with a 13 dB improvement in spurious-free dynamic range (SFDR).

Conclusions:

• The proposed linearization technique effectively improves analog photonic link linearity.
• The method offers substantial improvements in IMD3 suppression and SFDR.
• This approach is promising for applications requiring high-performance analog photonic links.